/*
** $Id: ldblib.c $
** Interface from Lua to its debug API
** See Copyright Notice in lua.h
*/

#define ldblib_c
#define LUA_LIB

#include "lprefix.h"


#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include "lua.h"

#include "lauxlib.h"
#include "lualib.h"


/*
** The hook table at registry[HOOKKEY] maps threads to their current
** hook function.
*/
static const char* const HOOKKEY = "_HOOKKEY";


/*
** If L1 != L, L1 can be in any state, and therefore there are no
** guarantees about its stack space; any push in L1 must be
** checked.
*/
static void checkstack(lua_State* L, lua_State* L1, int n) {
	if (L != L1 && !lua_checkstack(L1, n))
		luaL_error(L, "stack overflow");
}


static int db_getregistry(lua_State* L) {
	lua_pushvalue(L, LUA_REGISTRYINDEX);
	return 1;
}


static int db_getmetatable(lua_State* L) {
	luaL_checkany(L, 1);
	if (!lua_getmetatable(L, 1)) {
		lua_pushnil(L);  /* no metatable */
	}
	return 1;
}


static int db_setmetatable(lua_State* L) {
	int t = lua_type(L, 2);
	luaL_argexpected(L, t == LUA_TNIL || t == LUA_TTABLE, 2, "nil or table");
	lua_settop(L, 2);
	lua_setmetatable(L, 1);
	return 1;  /* return 1st argument */
}


static int db_getuservalue(lua_State* L) {
	int n = (int)luaL_optinteger(L, 2, 1);
	if (lua_type(L, 1) != LUA_TUSERDATA)
		luaL_pushfail(L);
	else if (lua_getiuservalue(L, 1, n) != LUA_TNONE) {
		lua_pushboolean(L, 1);
		return 2;
	}
	return 1;
}


static int db_setuservalue(lua_State* L) {
	int n = (int)luaL_optinteger(L, 3, 1);
	luaL_checktype(L, 1, LUA_TUSERDATA);
	luaL_checkany(L, 2);
	lua_settop(L, 2);
	if (!lua_setiuservalue(L, 1, n))
		luaL_pushfail(L);
	return 1;
}


/*
** Auxiliary function used by several library functions: check for
** an optional thread as function's first argument and set 'arg' with
** 1 if this argument is present (so that functions can skip it to
** access their other arguments)
*/
static lua_State* getthread(lua_State* L, int* arg) {
	if (lua_isthread(L, 1)) {
		*arg = 1;
		return lua_tothread(L, 1);
	}
	else {
		*arg = 0;
		return L;  /* function will operate over current thread */
	}
}


/*
** Variations of 'lua_settable', used by 'db_getinfo' to put results
** from 'lua_getinfo' into result table. Key is always a string;
** value can be a string, an int, or a boolean.
*/
static void settabss(lua_State* L, const char* k, const char* v) {
	lua_pushstring(L, v);
	lua_setfield(L, -2, k);
}

static void settabsi(lua_State* L, const char* k, int v) {
	lua_pushinteger(L, v);
	lua_setfield(L, -2, k);
}

static void settabsb(lua_State* L, const char* k, int v) {
	lua_pushboolean(L, v);
	lua_setfield(L, -2, k);
}


/*
** In function 'db_getinfo', the call to 'lua_getinfo' may push
** results on the stack; later it creates the result table to put
** these objects. Function 'treatstackoption' puts the result from
** 'lua_getinfo' on top of the result table so that it can call
** 'lua_setfield'.
*/
static void treatstackoption(lua_State* L, lua_State* L1, const char* fname) {
	if (L == L1)
		lua_rotate(L, -2, 1);  /* exchange object and table */
	else
		lua_xmove(L1, L, 1);  /* move object to the "main" stack */
	lua_setfield(L, -2, fname);  /* put object into table */
}


/*
** Calls 'lua_getinfo' and collects all results in a new table.
** L1 needs stack space for an optional input (function) plus
** two optional outputs (function and line table) from function
** 'lua_getinfo'.
*/
static int db_getinfo(lua_State* L) {
	lua_Debug ar;
	int arg;
	lua_State* L1 = getthread(L, &arg);
	const char* options = luaL_optstring(L, arg + 2, "flnSrtu");
	checkstack(L, L1, 3);
	if (lua_isfunction(L, arg + 1)) {  /* info about a function? */
		options = lua_pushfstring(L, ">%s", options);  /* add '>' to 'options' */
		lua_pushvalue(L, arg + 1);  /* move function to 'L1' stack */
		lua_xmove(L, L1, 1);
	}
	else {  /* stack level */
		if (!lua_getstack(L1, (int)luaL_checkinteger(L, arg + 1), &ar)) {
			luaL_pushfail(L);  /* level out of range */
			return 1;
		}
	}
	if (!lua_getinfo(L1, options, &ar))
		return luaL_argerror(L, arg + 2, "invalid option");
	lua_newtable(L);  /* table to collect results */
	if (strchr(options, 'S')) {
		lua_pushlstring(L, ar.source, ar.srclen);
		lua_setfield(L, -2, "source");
		settabss(L, "short_src", ar.short_src);
		settabsi(L, "linedefined", ar.linedefined);
		settabsi(L, "lastlinedefined", ar.lastlinedefined);
		settabss(L, "what", ar.what);
	}
	if (strchr(options, 'l'))
		settabsi(L, "currentline", ar.currentline);
	if (strchr(options, 'u')) {
		settabsi(L, "nups", ar.nups);
		settabsi(L, "nparams", ar.nparams);
		settabsb(L, "isvararg", ar.isvararg);
	}
	if (strchr(options, 'n')) {
		settabss(L, "name", ar.name);
		settabss(L, "namewhat", ar.namewhat);
	}
	if (strchr(options, 'r')) {
		settabsi(L, "ftransfer", ar.ftransfer);
		settabsi(L, "ntransfer", ar.ntransfer);
	}
	if (strchr(options, 't'))
		settabsb(L, "istailcall", ar.istailcall);
	if (strchr(options, 'L'))
		treatstackoption(L, L1, "activelines");
	if (strchr(options, 'f'))
		treatstackoption(L, L1, "func");
	return 1;  /* return table */
}


static int db_getlocal(lua_State* L) {
	int arg;
	lua_State* L1 = getthread(L, &arg);
	int nvar = (int)luaL_checkinteger(L, arg + 2);  /* local-variable index */
	if (lua_isfunction(L, arg + 1)) {  /* function argument? */
		lua_pushvalue(L, arg + 1);  /* push function */
		lua_pushstring(L, lua_getlocal(L, NULL, nvar));  /* push local name */
		return 1;  /* return only name (there is no value) */
	}
	else {  /* stack-level argument */
		lua_Debug ar;
		const char* name;
		int level = (int)luaL_checkinteger(L, arg + 1);
		if (!lua_getstack(L1, level, &ar))  /* out of range? */
			return luaL_argerror(L, arg + 1, "level out of range");
		checkstack(L, L1, 1);
		name = lua_getlocal(L1, &ar, nvar);
		if (name) {
			lua_xmove(L1, L, 1);  /* move local value */
			lua_pushstring(L, name);  /* push name */
			lua_rotate(L, -2, 1);  /* re-order */
			return 2;
		}
		else {
			luaL_pushfail(L);  /* no name (nor value) */
			return 1;
		}
	}
}


static int db_setlocal(lua_State* L) {
	int arg;
	const char* name;
	lua_State* L1 = getthread(L, &arg);
	lua_Debug ar;
	int level = (int)luaL_checkinteger(L, arg + 1);
	int nvar = (int)luaL_checkinteger(L, arg + 2);
	if (!lua_getstack(L1, level, &ar))  /* out of range? */
		return luaL_argerror(L, arg + 1, "level out of range");
	luaL_checkany(L, arg + 3);
	lua_settop(L, arg + 3);
	checkstack(L, L1, 1);
	lua_xmove(L, L1, 1);
	name = lua_setlocal(L1, &ar, nvar);
	if (name == NULL)
		lua_pop(L1, 1);  /* pop value (if not popped by 'lua_setlocal') */
	lua_pushstring(L, name);
	return 1;
}


/*
** get (if 'get' is true) or set an upvalue from a closure
*/
static int auxupvalue(lua_State* L, int get) {
	const char* name;
	int n = (int)luaL_checkinteger(L, 2);  /* upvalue index */
	luaL_checktype(L, 1, LUA_TFUNCTION);  /* closure */
	name = get ? lua_getupvalue(L, 1, n) : lua_setupvalue(L, 1, n);
	if (name == NULL) return 0;
	lua_pushstring(L, name);
	lua_insert(L, -(get + 1));  /* no-op if get is false */
	return get + 1;
}


static int db_getupvalue(lua_State* L) {
	return auxupvalue(L, 1);
}


static int db_setupvalue(lua_State* L) {
	luaL_checkany(L, 3);
	return auxupvalue(L, 0);
}


/*
** Check whether a given upvalue from a given closure exists and
** returns its index
*/
static int checkupval(lua_State* L, int argf, int argnup) {
	int nup = (int)luaL_checkinteger(L, argnup);  /* upvalue index */
	luaL_checktype(L, argf, LUA_TFUNCTION);  /* closure */
	luaL_argcheck(L, (lua_getupvalue(L, argf, nup) != NULL), argnup,
		"invalid upvalue index");
	return nup;
}


static int db_upvalueid(lua_State* L) {
	int n = checkupval(L, 1, 2);
	lua_pushlightuserdata(L, lua_upvalueid(L, 1, n));
	return 1;
}


static int db_upvaluejoin(lua_State* L) {
	int n1 = checkupval(L, 1, 2);
	int n2 = checkupval(L, 3, 4);
	luaL_argcheck(L, !lua_iscfunction(L, 1), 1, "Lua function expected");
	luaL_argcheck(L, !lua_iscfunction(L, 3), 3, "Lua function expected");
	lua_upvaluejoin(L, 1, n1, 3, n2);
	return 0;
}


/*
** Call hook function registered at hook table for the current
** thread (if there is one)
*/
static void hookf(lua_State* L, lua_Debug* ar) {
	static const char* const hooknames[] =
	{ "call", "return", "line", "count", "tail call" };
	lua_getfield(L, LUA_REGISTRYINDEX, HOOKKEY);
	lua_pushthread(L);
	if (lua_rawget(L, -2) == LUA_TFUNCTION) {  /* is there a hook function? */
		lua_pushstring(L, hooknames[(int)ar->event]);  /* push event name */
		if (ar->currentline >= 0)
			lua_pushinteger(L, ar->currentline);  /* push current line */
		else lua_pushnil(L);
		lua_assert(lua_getinfo(L, "lS", ar));
		lua_call(L, 2, 0);  /* call hook function */
	}
}


/*
** Convert a string mask (for 'sethook') into a bit mask
*/
static int makemask(const char* smask, int count) {
	int mask = 0;
	if (strchr(smask, 'c')) mask |= LUA_MASKCALL;
	if (strchr(smask, 'r')) mask |= LUA_MASKRET;
	if (strchr(smask, 'l')) mask |= LUA_MASKLINE;
	if (count > 0) mask |= LUA_MASKCOUNT;
	return mask;
}


/*
** Convert a bit mask (for 'gethook') into a string mask
*/
static char* unmakemask(int mask, char* smask) {
	int i = 0;
	if (mask & LUA_MASKCALL) smask[i++] = 'c';
	if (mask & LUA_MASKRET) smask[i++] = 'r';
	if (mask & LUA_MASKLINE) smask[i++] = 'l';
	smask[i] = '\0';
	return smask;
}


static int db_sethook(lua_State* L) {
	int arg, mask, count;
	lua_Hook func;
	lua_State* L1 = getthread(L, &arg);
	if (lua_isnoneornil(L, arg + 1)) {  /* no hook? */
		lua_settop(L, arg + 1);
		func = NULL; mask = 0; count = 0;  /* turn off hooks */
	}
	else {
		const char* smask = luaL_checkstring(L, arg + 2);
		luaL_checktype(L, arg + 1, LUA_TFUNCTION);
		count = (int)luaL_optinteger(L, arg + 3, 0);
		func = hookf; mask = makemask(smask, count);
	}
	if (!luaL_getsubtable(L, LUA_REGISTRYINDEX, HOOKKEY)) {
		/* table just created; initialize it */
		lua_pushstring(L, "k");
		lua_setfield(L, -2, "__mode");  /** hooktable.__mode = "k" */
		lua_pushvalue(L, -1);
		lua_setmetatable(L, -2);  /* metatable(hooktable) = hooktable */
	}
	checkstack(L, L1, 1);
	lua_pushthread(L1); lua_xmove(L1, L, 1);  /* key (thread) */
	lua_pushvalue(L, arg + 1);  /* value (hook function) */
	lua_rawset(L, -3);  /* hooktable[L1] = new Lua hook */
	lua_sethook(L1, func, mask, count);
	return 0;
}


static int db_gethook(lua_State* L) {
	int arg;
	lua_State* L1 = getthread(L, &arg);
	char buff[5];
	int mask = lua_gethookmask(L1);
	lua_Hook hook = lua_gethook(L1);
	if (hook == NULL) {  /* no hook? */
		luaL_pushfail(L);
		return 1;
	}
	else if (hook != hookf)  /* external hook? */
		lua_pushliteral(L, "external hook");
	else {  /* hook table must exist */
		lua_getfield(L, LUA_REGISTRYINDEX, HOOKKEY);
		checkstack(L, L1, 1);
		lua_pushthread(L1); lua_xmove(L1, L, 1);
		lua_rawget(L, -2);   /* 1st result = hooktable[L1] */
		lua_remove(L, -2);  /* remove hook table */
	}
	lua_pushstring(L, unmakemask(mask, buff));  /* 2nd result = mask */
	lua_pushinteger(L, lua_gethookcount(L1));  /* 3rd result = count */
	return 3;
}


static int db_debug(lua_State* L) {
	for (;;) {
		char buffer[250];
		lua_writestringerror("%s", "lua_debug> ");
		if (fgets(buffer, sizeof(buffer), stdin) == 0 ||
			strcmp(buffer, "cont\n") == 0)
			return 0;
		if (luaL_loadbuffer(L, buffer, strlen(buffer), "=(debug command)") ||
			lua_pcall(L, 0, 0, 0))
			lua_writestringerror("%s\n", luaL_tolstring(L, -1, NULL));
		lua_settop(L, 0);  /* remove eventual returns */
	}
}


static int db_traceback(lua_State* L) {
	int arg;
	lua_State* L1 = getthread(L, &arg);
	const char* msg = lua_tostring(L, arg + 1);
	if (msg == NULL && !lua_isnoneornil(L, arg + 1))  /* non-string 'msg'? */
		lua_pushvalue(L, arg + 1);  /* return it untouched */
	else {
		int level = (int)luaL_optinteger(L, arg + 2, (L == L1) ? 1 : 0);
		luaL_traceback(L, L1, msg, level);
	}
	return 1;
}


static int db_setcstacklimit(lua_State* L) {
	int limit = (int)luaL_checkinteger(L, 1);
	int res = lua_setcstacklimit(L, limit);
	if (res == 0)
		lua_pushboolean(L, 0);
	else
		lua_pushinteger(L, res);
	return 1;
}


static const luaL_Reg dblib[] = {
  {"debug", db_debug},
  {"getuservalue", db_getuservalue},
  {"gethook", db_gethook},
  {"getinfo", db_getinfo},
  {"getlocal", db_getlocal},
  {"getregistry", db_getregistry},
  {"getmetatable", db_getmetatable},
  {"getupvalue", db_getupvalue},
  {"upvaluejoin", db_upvaluejoin},
  {"upvalueid", db_upvalueid},
  {"setuservalue", db_setuservalue},
  {"sethook", db_sethook},
  {"setlocal", db_setlocal},
  {"setmetatable", db_setmetatable},
  {"setupvalue", db_setupvalue},
  {"traceback", db_traceback},
  {"setcstacklimit", db_setcstacklimit},
  {NULL, NULL}
};


LUAMOD_API int luaopen_debug(lua_State* L) {
	luaL_newlib(L, dblib);
	return 1;
}

